1. Field of the Invention
The invention relates to a process for the hydroprocessing of hydrocarbon feedstocks.
2. Discussion of the Prior Art
Catalysts comprising at least one Group VIII non-noble metal component and at least two Group VIB metal components, the Group VIII and Group VIB metal components making up at least 50 wt. % of the catalyst composition, calculated as oxides, are known in the art.
U.S. Pat. No. 4,596,785 describes a catalyst composition comprising the disulfides of at least one Group VIII non-noble metal and at least one Group VIB metal. U.S. Pat. No. 4,820,677 describes a catalyst comprising an amorphous sulfide comprising iron as the Group VIII non-noble metal and a metal selected from molybdenum, tungsten or mixtures thereof as the Group VIB metal, as well as a polydentate ligand such as ethylene diamine. In both references the catalyst is prepared via the co-precipitation of water-soluble sources of one Group VIII non-noble metal and two Group VIB metals in the presence of sulfides. The precipitate is isolated, dried, and calcined in an inert atmosphere, which means that sophisticated techniques are required to carry out these processes.
U.S. Pat. No. 3,678,124 discloses oxidic catalysts to be used in the oxidative dehydrogenation of paraffin hydrocarbons. The catalysts are prepared by co-precipitating water-soluble components of the Group VIB metals and Group VIII non-noble metals.
In WO 9903578 catalysts are prepared by co-precipitating specified amounts of a nickel, molybdenum, and tungsten source in the absence of sulfides.
Non-prepublished international patent application PCT/EP00/00354 (corresponds to U.S. patent application Ser. No. 09/482,811, filed Jan. 13, 2000, incorporated herein by reference thereto) describes the preparation of sulfided catalyst compositions by coprecipitation of at least one Group VIII non-noble metal component and at least two Group VIB metal components to form an oxygen-stable precipitate, which is subsequently sulfided. Non-prepublished international patent application PCT/EP00/00355 (corresponds to U.S. patent application Ser. No. 09/231,118, filed Jan. 15, 1999, incorporated herein by reference thereto) describes the preparation of a catalyst composition by contacting at least one Group VIII non-noble metal component and at least two Group VIB metal components in the presence of a protic liquid, wherein at least one of the metal components is at least partly in the solid state during contacting.
Although the catalysts of some of these references, in particular those of Non-prepublished international patent applications PCT/EP00/00354 and PCT/EP00/00355 show a high activity, there is still need for improvement thereof.